Conventional Drilling Technique Research Articles

Multi response optimization of process parameters in titanium alloy minimum quantity lubrication drilling operation

Abstract This work investigates the application of minimal quantity lubrication (MQL) in the drilling process, where a combination of liquid and air creates an aerosol in the form of a fine mist. This protective layer decreases friction and tool wear, hence improving overall efficiency. The study examines the conventional Gulfcut oil blend drilling technique to enhance drilling performance on the titanium alloy Ti-6Al-4V under MQL circumstances. The key drilling parameters, namely spindle speed (N), feed rate (F), and point angle (D), were analyzed using a Taguchi L16 orthogonal array. The experimental inquiry aimed to identify the most favorable conditions that lead to the least amount of torque (TQ), thrust force (TF), and surface roughness (SR). An Analysis of Variance (ANOVA) was used to examine the impact of control factors on drilling performance. The optimized drilling parameters led to a reduction in torque, thrust force, and surface roughness by 12.88%, 21.29%, and 25.76%, respectively. Furthermore, microstructure analysis demonstrated that the Gulfcut lubricant plays a pivotal role in reducing grain size during drilling. This research provides valuable insights into optimizing drilling conditions for titanium alloy using a conventional Gulfcut oil blend with MQL, aiming to reduce torque, thrust force, and surface roughness.

Heat Generation and Pain Assessment in Piezosurgery Versus Conventional Drilling for Implant Placement: A Systematic Review.

The development of new technologies in implant dentistry has led to the introduction of piezosurgery, which utilizes ultrasonic vibrations for micrometric and selective bone cutting. It is hypothesized to reduce trauma to bone tissue, thereby potentially improving the healing process compared to traditional drilling methods. This systematic review examines the differences in heat generation and pain perception between piezosurgery and conventional drilling techniques for dental implant placement. An extensive review of literature was performed using various databases, includingPubMed via MEDLINE, EBSCO, and Google Scholar. Out of an initial pool of 2,279 articles, nine studies met the predefined inclusion criteria and were included in the final analysis following title and abstract screening and subsequent full-text evaluation. The quality of the selected studies was rigorously assessed using the Risk of Bias (RoB 2.0), Risk of Bias in Non-randomized Studies - of Interventions (ROBINS-I), and Quality Assessment Tool for In Vitro Studies (QUIN) tools. Data pertaining to thermal effects and postoperative pain associated with piezosurgery relative to conventional drilling protocols were collected. The results indicated a significant reduction in postoperative pain with piezosurgery; however, the technique was associated with higher intraoperative temperatures during osteotomy. These findings provide valuable insights into the potential benefits and limitations of piezosurgery in dental implant procedures.

Unlocking implant success: the impact of surgical techniques on primary stability in the posterior maxilla.

The study conducted by Olmedo-Gaya et al. aimed to investigate the effects of various surgical techniques on the initial stability of implants placed in the posterior maxilla through a randomized controlled clinical trial. The study compared insertion torque (IT) and implant stability quotients (ISQ) among implants placed using under preparation, expanders, and standard surgical instrumentation. The study enrolled 108 patients, each receiving one implant in the posterior maxilla region. Patients were distributed into three groups: group 1 (n = 36) with the under preparation technique, group 2 (n = 36) using the expander technique, and group 3 (n = 36) with conventional drilling. IT was measured using a torque indicator, while ISQ was recorded through resonance frequency analysis immediately post-surgery. The ISQ values were analyzed in relation to the patient's bone quality, categorized into types II, III, and IV. ISQ values varied significantly with bone quality, being highest in type II (76.65) and type III (73.60), and lowest in type IV (67.34) bone, with a significant difference (p < 0.0001). The conventional drilling technique yielded lower ISQ values (69.31) compared to under preparation (74.29) and expander techniques (73.99), with statistical significance (p = 0.008 and p = 0.005, respectively). Surgical technique significantly influences primary stability in low-quality bone. Conventional drilling results in lower ISQ values, suggesting that alternative techniques such as under preparation or expanders should be used in low-quality bone to achieve better primary stability. For implants in low-quality bone, replacing the conventional drilling technique with under preparation or expander techniques can enhance primary stability.

Comparative evaluation of osseodensification drilling versus conventional drilling technique on dental implant stability: A systematic review.

The present systematic review compares the stability, crestal bone levels and efficacy of osseodensification (OD) drilling techniques for dental implant placement to traditional drilling methods. The Cochrane online library, PubMed, Scopus, and other well-known online resources are used in the research. Using a systematic review design, the current study examines published qualitative studies with an emphasis on analysis. Using precise keywords, a thorough search of pertinent databases was carried out in accordance with PRISMA standards. Studies testing dental implant stability, crestal bone levels and clinical results using both OD and traditional procedures were covered by the inclusion criteria. The risk of bias and quality of included studies was assessed using the Newcastle-Ottawa Scale for observational studies and the Cochrane Risk of Bias tool for randomized controlled trials. A total of 170 patients and 334 implants from Egypt, India, and Brazil were included in eight papers that made up the systematic review. In several clinical situations, osseodensification outperformed standard drilling in terms of implant durability, bone development, and torque data. Statistical analysis presented the lowest risks, while blinded outcome assessment, allocation concealment, random sequence generation, incomplete outcome data and experimental technique revealed higher risks. Bias assessment found various risks across different components. The thorough examination of eight papers demonstrates that osseodensification is a technique with great promise in the field of dental implants. It exhibits superior torque values, bone development, and stability when compared to traditional drilling. The overall results highlight the potential of osseodensification to improve clinical outcomes and advance the science of dental implantology, even in the face of variances in bias concerns.

Evaluation of different well control methods concentrating on the application of conventional drilling technique

Over the past few decades, engineering failures have existed, and lack of knowledge, and safety practices have led to various catastrophic events of blowouts causing countless casualties and injuries to workers and individuals all around the world. Well control is a technique in oil and gas activities specifically when drilling oil and gas wells. Hydrostatic pressure and formation pressure should be a priority to prevent reservoir fluids from infiltrating the wellbore. The primary well control is commonly the primary barrier using the fluid column to prevent uncontrolled formation fluid flow into the wellbore by preserving pressure more substantial than formation pressure. The secondary well control provides the same purpose but involves using a piece of equipment known as a Blowout Preventer. The objective of this paper is to evaluate the effectiveness of different well control techniques of various well control methods, including the commonly used in petroleum engineering focusing on the application of conventional drilling. This study was conducted through a literature review. The analysis of the case studies synthesized to provide a comprehensive overview of the various well control methods. The findings suggested that conventional drilling techniques can be effective in controlling wellbore pressures, however, limitations existed in certain situations. Moreover, the parameters required controlling the well during a kick or a blowout is discussed to succeed in the application of well control methods in the oil and gas industry.

Semi-autonomous two-stage dental robotic technique for zygomatic implants: An in vitro study

ObjectiveTo assess the feasibility and accuracy of a semi-autonomous two-stage dental robotic technique for zygomatic implants. MethodsTwenty-six zygomatic implants were designed and randomly divided into two groups using 10 three-dimensionally printed resin models with severe maxillary atrophy. In one group, the conventional drilling technique was used, in the other group, the drilling process for the alveolar ridge section (first stage) was completed, after which drilling for the zygoma section (second stage) was done. Based on preoperative planning combined with postoperative cone-beam computed tomography (CBCT), coronal, apical, depth, and angle deviations were measured. Zygomatic implant placement technique-related deviations (sinus slot, intrasinus, and extrasinus) were also recorded and analyzed. ResultsThe two-stage technical group's coronal, apical, depth, and angle deviations were 0.57 ± 0.19 mm, 1.07 ± 0.48 mm, 0.30 ± 0.38 mm, and 0.91 ± 0.51°, respectively. The accuracy of the two-stage technique was significantly higher than that of the conventional one-stage technique (p < 0.05). The apical deviation in the intrasinus group was 1.12 ± 0.56 mm, which was significantly better than that in the other two groups (p < 0.05). The angle deviation in the sinus slot group was 1.96 ± 0.83°, which was significantly worse than that in the other two groups (p < 0.05). ConclusionUsing the semi-autonomous two-stage dental robotic technique for zygomatic implants is feasible and is more accurate than using the conventional one-stage technique. Clinical significanceThe two-stage technique enabled the semi-autonomous robot to overcome the mouth-opening restriction for zygomatic implants and improved accuracy.

Anatomic Double-Bundle Anterior Cruciate Ligament Reconstruction Using the Anatomic Double-Bundle 2-in-1 Guide System

Background: In double-bundle anterior cruciate ligament (ACL) reconstruction, tunnel coalition may occur intraoperatively or during the postoperative course. Tibial tunnel coalition is more common compared with femoral tunnel coalition. Once tunnel coalition occurs on the tibial side, rotatory knee laxity may not be controlled as expected. We have developed a new device to avoid tibial tunnel coalition with consistency. The purpose of this video is to present the surgical technique for double-bundle ACL reconstruction using a new drill guide. Indications: The novel guide may be used in all cases with confirmed ACL tear in a physically active patient, identical to indications for current ACL reconstruction using the double-bundle technique. Technique Description: The hamstring tendon is harvested for the ACL grafts. Two guide pins for the anteromedial bundle and posterolateral bundle for the tibial tunnel are inserted through the Anatomic Double-Bundle 2-in-1 Guide System. Cannulated drills and dilators are used to create the tunnel to the final diameter. Next, femoral tunnels are created by the outside-in technique using the Anatomic Double-Bundle 2-in-1 Guide System. Grafts are inserted from the tibia and passed through the femur. The grafts are fixed with a post screw and/or interference screw. Results: Two weeks after surgery, no tibial or femoral coalition (0/20 cases) were confirmed and tibial bony bridge at the intraarticular surface was measured 2.7 ± 0.9 mm using computed tomography (CT). One year after surgery, tibial coalition was confirmed in 13.3% (2/15 cases), and femoral coalition in 6.7% (1/15 cases) on CT image mainly due to tunnel widening. The 2 cases with tibial coalition had tibial bony bridge of less than 2 mm on immediate postoperative CT. Discussion/Conclusion: Using the novel guide, 2 tibial tunnels were created easily and accurately compared with the conventional independent drilling technique. The 2 tunnels can also be created simultaneously with single placement of the guide. Two separate tunnels help maintain expected rotatory knee stability after double-bundle ACL reconstruction. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Reducing the taper and the heat-affected zone of CFRP plate by Micro fluid assisted laser induced plasma micro-drilling

Carbon Fiber Reinforced Plastics (CFRP) with superior mechanical properties are widely used in aerospace, automotive, and medical fields. The characteristics of CFRP with anisotropy and inhomogeneous result in poor machining performances by conventional drilling techniques. Laser drilling is a non-contact high precision machining technique without tool wear but leads to a large heat-affected zone (HAZ) and taper. Although underwater laser drilling could reduce thermal damage on CFRP surface, bubbles produced in the machining process severely affect the machining stability and surface quality. In this study, a micro fluid-assisted laser-induced plasma drilling (MFA-LIPMD) method was proposed to relieve the negative effect of bubbles as well as reduce the taper and HAZ. A comprehensive analysis of hole surface quality, HAZ, taper, and mechanical properties was conducted, and MFA-LIPMD performed more advantages over laser in the air (LIA) and laser-induced plasma drilling (LIPMD). It was found that the taper of micro-holes was reduced by 42.8%–51.78%, and the thermal damage rate of micro holes processed by the MFA-LIPMD process was reduced by 65.3%–68.1% compared with the LIPMD process, and the maximum tensile load of samples was increased by about 7.68%. Therefore, MFA-LIPMD has great potential for machining high-quality micro holes of CFRP plates.

Drilling Optimization by Using Advanced Drilling Techniques in Buzurgan Oil Field

Efficient and cost-effective drilling of directional wells necessitates the implementation of best drilling practices and advanced techniques to optimize drilling operations. Failure to adequately consider drilling risks can result in inefficient drilling operations and non-productive time (NPT). Although advanced drilling techniques may be expensive, they offer promising technical solutions for mitigating drilling risks. This paper aims to demonstrate the effectiveness of advanced drilling techniques in mitigating risks and improving drilling operations when compared to conventional drilling techniques. Specifically, the advanced drilling techniques employed in Buzurgan Oil Field, including vertical drilling with mud motor, managed pressure drilling (MPD), rotary steerable system (RSS), and expandable liner hanger (ELH), are investigated and evaluated through case study analyses, comparing their performance to that of conventional drilling techniques. The findings indicate that vertical drilling with mud motor exhibits superior drilling performance and wellbore verticality compared to conventional rotary drilling bottom hole assemblies (BHA) for drilling the 17 ½" hole section. MPD systems employed in the 12 ¼" hole section demonstrate safe drilling operations and higher rates of penetration (ROP) than conventional drilling methods. Rotary steerable systems exhibit reduced tortuosity and achieve higher ROP when compared to mud motor usage in the 8.5" and 6" hole sections. Lastly, investigations of expandable liner hanger cases reveal subpar cement quality in the first case and liner remedial work in the second case, highlighting the successful implementation of ELH techniques in the offset field. Overall, this paper highlights the advantages of utilizing advanced drilling techniques in Buzurgan Oil Field, showcasing their ability to mitigate drilling risks and enhance drilling operations when compared to conventional drilling approaches.

Influence of different surgical techniques on primary implant stability in the posterior maxilla: a randomized controlled clinical trial

Background and objectivePrimary stability (PS) is remarkable for secondary stability and implant success. Surgical technique modifications seem to improve primary stability, especially in poor quality bone. The aim of this study was to compare the insertion torque (IT) and implant stability quotients (ISQ) of implants placed with underpreparation, expanders, and standard surgical instrumentation in different bone types.Material and methodsThis randomized controlled clinical trial enrolled 108 patients (n=108 implants) distributed in three study groups: group 1 (n=36) underpreparation technique, group 2 (n=36) expander technique, and group 3 (n=36) conventional drilling. IT was recorded with a torque indicator. ISQ was recorded with resonance frequency analysis immediately after surgery.ResultsISQ values were associated with the patient’s bone quality and were higher in bone quality type II (76.65) and type III (73.60) and lower in bone quality type IV (67.34), with statistically significant differences (p<0.0001). Lower stability results were obtained when conventional drilling (69.31) was used compared to the use of underpreparation (74.29) or expanders (73.99) with a level of significance of p=0.008 and p=0.005, respectively.ConclusionsThe surgical technique influences the PS when there is low-quality bone. In low-quality bones, conventional drilling obtains lower ISQ values.Clinical relevanceReplace the conventional drilling technique for an alternative, underpreparation or expanders, in low-quality bone in order to achieve greater primary stability.

Evaluation of Change in Radiographic Fractal Dimension around Dental Implants Placed with Low-Speed Drilling and Standard Drilling Protocols.

Establish box-counting dimension values for radiological images in patients with implants placed with both drilling methods. The sample included 129 implants corresponding to 50 patients. A double-blind study of data collection was carried out with the subsequent analysis of the fractal dimension as a comparative value of the state of the trabecular architecture. We found no significant differences (p ≥ 0.05) between the two study groups comparing both drilling techniques. The values for the conventional drilling technique are 0.24 ± 0.07 and for biological drilling: 0.19 ± 0.11 with a p-value of 0.767. The drilling technique does not influence the success of the procedure and the osseointegration process.

The Effect of Osseodensification on Ridge Expansion, Intraosseous Temperature, and Primary Implant Stability: A Pilot Study on Bovine Ribs.

Osseodensification is a novel technique based on nonsubtractive drilling to preserve and condense bone during osteotomy preparation. The aim of this ex vivo study was to compare osseodensification and conventional extraction drilling technique with regard to intraosseous temperatures, expansion of alveolar ridge width, and primary implant stability using different implant geometries: tapered and straight walled. A total of 45 implant sites were prepared in bovine ribs following osseodensification and conventional protocols. Changes in intraosseous temperatures were recorded at 3 depths using thermocouples, and ridge width was measured at 2 different depths before and after osseodensification preparations. The primary implant stability was measured using peak insertion torque and the implant stability quotient (ISQ) following placement of straight and tapered implants. A significant change in temperature was recorded during site preparation for all techniques tested but not at all depths. Osseodensification recorded higher mean temperatures (42.7°C) than conventional drilling, particularly at the midroot level. Statistically significant ridge expansion was observed at both the crestal and apical levels in the osseodensification group. The ISQ values were significantly higher only for tapered implants placed in osseodensification sites when compared with conventional drilling sites; however, there was no difference in the primary stability between tapered and straight implants within the osseodensification group. Within the limitations of the present pilot study, osseodensification was found to increase the primary stability of straight-walled implants without overheating the bone and significantly expanded the ridge width. However, further investigation is required to determine the clinical significance of the bone expansion created by this new technique.

Marginal integrity of composite resin restoration in class I cavities prepared by hydro-abrasion

Aim To evaluate and compare the marginal integrity of composite resin restorations made by two different preparation techniques: conventional drill and hydro-abrasion. Materials and methods Forty extracted human premolars with simple occlusal caries were used. The teeth were fixed with sticky wax to the base of plastic cylinder. The cylinder was filled with self-curing acrylic resin so that only root was embedded within the self-curing acrylic resin. The teeth were randomly divided into two main groups (n = 20) according to the preparation technique. Group I: class I cavity preparation was done by the conventional drill method using a #245 Carbide bur and contra angle high-speed hand piece with water coolant. Cavity design was restricted to remove caries with no undercuts, and no beveling. Group II: class I cavity preparation was done by Aquacut Quattro air hydro-abrasion unit which uses a gamma irradiated aluminum oxide particle as abrasives (29 μm), cutting fluid and a hand piece of 0.6 mm diameter tip. The preparation in both groups was restored by the same composite resin (Grandio) and adhesive systems (Futurabond U) following the manufacturer's instructions. All specimens were thermocycled. Impressions for each tooth was made using a polyvinyl Siloxane material. The impressions were then poured with epoxy resin. These replicas were examined under scanning electron microscope. Scanning electron microscope photographs of tested samples were used for the gap evaluation. Results It was found that, group I recorded higher mean value of marginal gap length (157.57 ± 35.15 μm) than group II that recorded (69.55 ± 20.02 μm). Also, group I recorded higher mean value of marginal gap length ratio (10.72 ± 2.47) than group II that recorded (7.44 ± 2.69). Conclusion Conventional drilling technique was faster than the hydro-abrasion technique for cavity preparation. Hydro-abrasion technique showed more marginal adaptation than conventional drilling technique.

Resonance Frequency Analysis to Evaluate the Effect of Different Drilling Techniques on Implant Stability at Different Time Intervals: A Randomized Clinical Trial.

To evaluate the effect of different drilling techniques on implant stability at different time intervals. Patients were randomly allotted into three groups based on drilling technique for osteotomy: conventional drilling technique; simplified drilling technique; or modified conventional drilling technique. In 30 patients (n = 10 each group), a total of 44 implants were placed. In the conventional drilling technique, drills with increasing diameters were used. In the simplified drilling technique, only pilot and final-diameter drills were used. In the modified conventional drilling technique, all the drills were used in sequential order in the clockwise direction except the last drill, which was used in the counterclockwise direction. Implant stability quotient was recorded immediately after placing implants and at 1 and 3 months. Statistical analysis was performed with two-way analysis of variance (ANOVA) and Student t test. Two-way ANOVA showed that drilling technique (P < .001) and time (P = .002) did have a statistically significant effect on implant stability quotient. The modified conventional drilling technique showed a drop in secondary implant stability at 1 month that was negligible compared to the other techniques. After 1 month, there was a significant increase in implant stability quotient with the modified conventional drilling technique compared to the conventional drilling technique (P = .001). The least crestal bone loss during 3 months of follow-up was with the modified conventional drilling technique (0.37 ± 0.06). Secondary stability increased with the modified conventional drilling technique in 3 months and showed a negligible drop at 1 month. This novel drilling technique had an early shift from a decrease to an increase in stability pattern, along with the least crestal bone loss at 3 months.

A dynamic event tree for a blowout accident in an oil deep-water well equipped with a managed pressure drilling condition monitoring and operation system

Blowout is one of the most dreaded accidents for Oil and Gas companies. It is of particular concern during the drilling phase of deep-water oil & gas wells. This is due to the largely uncertain and extremely harsh environmental conditions that affect the design, drilling and operation activities of these wells. Seeking new technological solutions to prevent blowout has led, in the last few decades, to develop Managed Pressure Drilling (MPD) techniques.MPD offers many advantages compared to conventional drilling techniques, such as the capability (1) to detect the gas influx that initiates the kick that might lead to blowout and (2) to optimally control and circulate out this influx, to avoid the blowout. Nevertheless, effects of uncertainties on the MPD functionality are not fully understood and satisfactorily modelled within conventional safety assessment that relies on Event Trees (ETs).In this work, we propose a Dynamic Event Tree (DET) modelling framework of the scenario of kick escalation into blowout to allow accounting for the uncertainties that affect not only the kick variables, but also for the fundamental role played by the time and the delay of the kick detection task. The uncertainties affecting the kick variables are evaluated from kick events records taken from 2000 oil wells drilled in the Niger Delta, whereas the uncertainties affecting the time and delay of kick detection are evaluated by simulating the performance of the tool embedded into the MPD for kick detection (which applies the CUSUM statistical test to differential flow measurements), and assuming a possibilistic distribution for the confirmation time needed by the operator to take counteracting measures with respect to the evolving accidental scenario.A Hybrid Monte Carlo and Possibilistic method is utilized to represent and propagate uncertainties associated to the events occurring throughout the DET. Results are compared with those of a Purely Probabilistic method in support of the blowout probability quantification.

ΟSSEODENSIFICATION. A PROMISING NEW TECHNIQUE.

INTRODUCTION: The technique of Οsseodensification has recently appeared in clinical practice by Salah Huwais for the placement of dental implants. This technique relies on the use of special burs (Versah), which in contrast to the conventional drilling techniques these burs do not excavate bone. PURPOSE: To highlight the importance of Οsseodensification in clinical practice. METHOD: A literature review for the last five years was performed, with keywords such as: Implant stability, osseodensification, osteotomy. RESULTS: During osteotomy, unlike conventional implant drills, the bone is advanced into the implant shaft instead of being removed. Versah burs allow for more accurate osteotomy preparation and reduce any potential drilling vibrations. With these special burs we have the ability to push the bone towards the base of the implant lumen. Finally, a closed sinus lift can be achieved by lifting the sinus membrane up to 3 mm without the use of a foreign graft. CONCLUSIONS: Οsseodensification has helped the clinician to achieve the maximum possible primary stability during the placement of the implant. The fact is, however, that there is a lack of sufficient documentation. It is therefore necessary to carry out more clinical studies, so as to lead to safer conclusions about the long-term results of the above technique.

The Effect of Under-Drilling and Osseodensification Drilling on Low-Density Bone: A Comparative Ex Vivo Study

The aim of this study is to identify a method that can maximize implant primary stability (IPS) and bone density under the controlled drilling conditions of the same diameter and length in low-density bones through an ex vivo study. A total of 87 dental implants were placed with standard drilling, under-drilling, and osseodensification drilling in 13 fresh porcine sternums. The Periotest value and the implant stability quotient were measured to evaluate the primary stability. The difference in the Hounsfield unit (HU) between the hole and peripheral bone up to a distance of 1 mm was measured. Osseodensification and under-drilling technique increased the IPS, compared with conventional drilling technique with statistical significance under the drilling conditions of the same diameter and length. Osseodensification technique with the counter-clockwise direction had higher HU gaps than the standard drilling and osseodensification technique with clockwise direction. Due to the effect of bone densification, the gap of HU was increased by a minimum of 43 HU and a maximum of 180 HU. Within the limitations of this ex vivo study, it was found that the osseodensification technique with counter-clockwise direction is effective to increase IPS and bone mineral density in low-density bone.

An analytical study on early kick detection and well control considerations for casing while drilling technology

Casing while drilling (CwD) technology is designed to reduce drilling time and expenses by improving the wellbore stability, fracture gradient, and formation damage while reducing the exposure time. However, for the purpose well control, the wellbore geometry and volumes differ from those obtained via a conventional drilling technique, thereby requiring a different approach. This study discusses well control principles for CwD operations. It presents a simplified method for evaluating the maximum kick tolerance and allowable well shut-in time for both conventional and CwD techniques using a mathematical model. Preliminary results revealed that the use of CwD leads to an annulus pressure loss three times higher than that observed in the conventional drilling. In addition, the kick tolerance is reduced by 50% and the maximum allowable well shut-in time is reduced by 65%, making an early kick detection system necessary.

Dynamic and quantitative risk assessment under uncertainty during deepwater managed pressure drilling

Risk assessment plays an important role in facilitating the safety and sustainability of deepwater drilling. Managed pressure drilling is increasingly used as an alternative to conventional drilling techniques. This technique increases the complexity and uncertainty of drilling systems with enhancement and advancement of functions. This paper presents a dynamic Bayesian network for risk assessment of managed pressure drilling. The method follows four basic steps including risk identification, topology construction, uncertainty characterization, and consequence evaluation. An event tree-fault tree model was established to develop potential accident scenarios and mapped into a Bayesian network to capture interdependencies and conditional relationships among the contributing factors. Both stochastic uncertainties and fuzzy uncertainties of risk factors are considered in the determination of failure probabilities. Degradation effects of equipment components are included in the forward reasoning of Bayesian network. The case study shows that the initial probability of the blowout is 2.28 × 10−5 and increases to 1.28 × 10−4 in ten time-intervals. Decision makers can take measures to prevent, eliminate, or mitigate accidents of deepwater drilling based on the evaluation results.

Osseodensification enables bone healing chambers with improved low-density bone site primary stability: an in vivo study

Primary implant stability is a prerequisite for successful implant osseointegration. The osseodensification technique (OD) is a non-subtractive drilling technique that preserves the bone tissue, increases osteotomy wall density, and improves the primary stability. This study aimed to investigate the hypothesis that OD, through a wider osteotomy, produces healing chambers (HCs) at the implant-bone interface without impacting low-density bone primary stability. Twenty implants (3.5 × 10 mm) with a nanohydroxyapatite (nHA) surface were inserted in the ilium of ten sheep. Implant beds were prepared as follows: (i) 2.7-mm-wide using subtractive conventional drilling (SCD) technique (n = 10); (ii) 3.8-mm-wide using an OD bur system (n = 10). The sheep were randomized to two groups, with samples collected at either 14-(n = 5) or 28-days (n = 5) post-surgery and processed for histological and histomorphometric evaluation of bone-implant contact (BIC) and bone area fraction occupancy (BAFO). No significant group differences were found with respect to final insertion torque and implant stability quotient (p > 0.050). BIC values were higher for SCD after 14 and 28 days (p < 0.050); however, BAFO values were similar (p > 0.050). It was possible to conclude that the OD technique allowed a wider implant bed preparation without prejudice on primary stability and bone remodeling.